Composition comprising saturated hydrocarbon and method for dust suppression

ABSTRACT

A composition for suppressing dust particles includes from about 51% to about 100% by weight of saturated hydrocarbons, and from about 0 to about 49% by weight of unsaturated hydrocarbons. The composition has a content of wax in the range from about 5% to about 40% by weight of the total composition. A method of making and a method of using such a composition are also provided.

PRIORITY CLAIM AND CROSS-REFERENCE

This Application is a continuation of U.S. patent application Ser. No.14/383,314, now U.S. Pat. No. 10,066,139, filed Sep. 5, 2014 as anational stage application of International Application No.PCT/US2014/053719, filed Sep. 2, 2014, which applications are expresslyincorporated by reference herein in their entirety.

FIELD

The disclosure relates to hydrocarbon based compositions and their use.More particularly, the disclosed subject matter relates to a compositioncomprising hydrocarbon, a method of making such a composition, a methodfor using such a composition for suppressing dust, and a system for dustsuppression.

BACKGROUND

The problems of fugitive dust are well known and encountered in theconstructions industries, the coal industry, and other miningindustries. Fugitive dust even exists in agriculture and food processingindustries. Dust and other solid particles can also be suspended in airand pose environmental issues in populated or environmentally sensitiveareas. Such particles also pose detrimental health effects.

One example, hydraulic fracturing, known as “fracking” or“hydrofracking” in the oil and gas industry, is the propagation offractures in a rock layer to enhance the release of oil and natural gasinto the well bore for extraction and subsequent refining. In hydraulicfracturing, a proppant is used at a large amount to keep the fracturesin the rock open. Hundreds of tons of proppant are used for fracturing awell. The proppant often contains silica such as silica sand, or resincoated silica sand. When the proppant is processed, large amounts ofdust containing silica and other components are evolved. The silica dustis created during the movement of the proppant by shearing of the sandparticles as they slide along one another. In addition to potentialcontamination of the air and water nearby, the silica dust also exposesworkers at the well site, at the mines and at the processing facilitiesto possible inhalation. Such an exposure can lead to a lung diseasecalled silicosis.

Silicosis is a form of an occupational lung disease caused by inhalationof crystalized silica dust. It is characterized by inflammation andscarring in forms of nodular lesions in the upper lobes of the lungs.When small silica dust particles are inhaled (<10 μm) they can imbedthemselves in the air exchange portion of workers' lungs (alveoli). Thelungs cannot clear themselves of the imbedded dust by mucous orcoughing, thus chronic exposure to respirable silica can cause a buildupof these particles and lead to silicosis.

Conventional dust suppression systems include both mechanical andchemical methods. Dust collection equipment includes devices whichcapture entrained dust, induce the dust to settle, or contain the dust.The most common method, however, is the wetting of dust particles (suchas coal) with water. Water is inexpensive and large quantities can beapplied. However, its effectiveness as a dust suppressant is less thansatisfactory. The addition of water may cause additional problems suchas a decrease in the specific heating value of coal. Other aqueousadditives such as surfactants or foaming agents, and aqueouscompositions comprising asphalt emulsions or other organic coatingmaterials are also used to suppress dust. In addition to aqueoussolutions, oils and resins are also used to reduce or eliminate coaldust. Oil spraying includes the use of crude, residual, waste or fueloils. Synthetic and natural polymers can be coated onto coal to reducedust. However, the prior additives and compositions have limitedapplicability and effectiveness.

SUMMARY OF THE INVENTION

The present invention provides a composition for suppressing dustparticles, the method of making and the method of using such acomposition.

In some embodiments, the composition for suppressing dust particlescomprises saturated hydrocarbons and unsaturated hydrocarbons. Forexample, the composition comprises from about 51% to about 100% byweight of saturated hydrocarbons (e.g., paraffin and cyclic saturatedhydrocarbons), and from about 0 to about 49% by weight of unsaturatedhydrocarbons (e.g., aromatic hydrocarbons). The composition has acontent of wax, which can be a part of the saturated and the unsaturatedhydrocarbons, in the range from about 5% to about 40% by weight of thetotal composition.

In some embodiments, the saturated hydrocarbons and the unsaturatedhydrocarbons are hydrocarbons in the range of from C6 to C61. In someembodiments, the saturated hydrocarbons comprise hydrocarbonssubstantially in the range of from C16 to C26. In some embodiments, thesaturated hydrocarbons can comprise paraffin in the range of from about61% to about 99.9% by weight of the total composition. The unsaturatedhydrocarbons are in the range of from about 5% to about 30% (e.g., fromabout 10% to about 20%) by weight of the total composition.

The wax may be paraffinic wax. The wax may also be saturated hydrocarbonin the range from C27 to C61. The content of the wax can be in the rangefrom about 5% to about 30% (e.g., 10-20%) by weight of the totalcomposition. In some embodiments, the wax has a boiling point of equalto or higher than 376° C. measured under atmospheric pressure. Forexample, the saturated hydrocarbons and the unsaturated hydrocarbons mayhave a boiling point in the range from about 285° C. to about 405° C.,and from about 60% to about 95% by weight of total composition has aboiling point of in the range of from 285° C. to 376° C. The boilingpoints are all measured under atmospheric pressure. In some embodiments,the composition as dust suppressant has a melting point of in the rangeof from 0° C. to 37.7° C.

In some embodiments, the saturated hydrocarbons further comprise atleast one cyclic saturated hydrocarbon, which is in the range from about0.1% to about 10% by weight of the total composition.

In some embodiments, the present disclosure provides an exemplarycomposition. In such an exemplary composition, the saturatedhydrocarbons are in the range of from about 80% to about 95% by weightof the total composition. The wax is a portion of the saturatedhydrocarbons and is in the range from about 10% to about 20% by weightof the total composition. The unsaturated hydrocarbons are aromatichydrocarbons, and are in the range of from about 5 to about 20% byweight of the total composition.

In another aspect, the present disclosure provides a method of makingthe composition for suppressing dust particles described herein. Themethod of making the composition comprises fractionally distilling afraction from a crude oil. The fraction comprises saturated andunsaturated hydrocarbons in the range of from C6 to C61.

Such a method further comprises hydrogenating (also known ashydrotreating process) the fraction to convert at least a portion of theunsaturated hydrocarbons to saturated hydrocarbons. In some embodiments,the unsaturated hydrocarbons in the fraction comprise aromatichydrocarbons, and at least a portion of the aromatic hydrocarbons isconverted into cyclic saturated hydrocarbons after the step ofhydrogenating. Sometimes the unsaturated hydrocarbons in the fractionmay comprise olefin (e.g., <5 wt. % or <2 wt. %). The olefin isconverted into saturated hydrocarbon after the step of hydrogenating.The degree of the hydrogenation in the step of hydrogenating is in therange from 10% to 95% by weight (e.g., 10%-75% or 20%-40%) of theunsaturated hydrocarbons in the fractions.

In another aspect, the present disclosure provides a method of using thecomposition for suppressing particles described herein. The method ofusing the composition comprises applying the composition to bring thecomposition in contact with the particles. The step of applying thecomposition may comprise a step of mixing the composition with theparticles, or a step of spraying the composition onto with theparticles, or any combinations thereof. In some embodiments, thecomposition is sprayed into drops having a size substantially similar orclose to (or the same as) the size of the particles. The method of usingcan further comprise heating the composition before or during the stepof applying the composition, at a temperature of in the range from 10°C. to 100° C. (e.g., from 37° C. to 70° C. or from 20 to 25° C.).

In another aspect, a system for making the composition or using thecomposition described herein are also provided.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read in conjunction with the accompanying drawings. Itis emphasized that, according to common practice, the various featuresof the drawings are not necessarily to scale. On the contrary, thedimensions of the various features are arbitrarily expanded or reducedfor clarity. Like reference numerals denote like features throughoutspecification and drawings.

FIG. 1 illustrates a crude tower for separating hydrocarbons throughfractional distillation in accordance with some embodiments.

FIG. 2 is the distillation chart of an exemplary hydrocarbon fractionwaxy LLN used in some embodiments.

FIG. 3 is the distillation chart of hydrogenated waxy LLN as anexemplary dust suppressant composition in some embodiments.

FIGS. 4A-4C illustrate the apparatus for testing dust suppression usedin some embodiments.

DETAILED DESCRIPTION

This description of the exemplary embodiments is intended to be read inconnection with the accompanying drawings, which are to be consideredpart of the entire written description. In the description, relativeterms such as “lower,” “upper,” “horizontal,” “vertical,”, “above,”“below,” “up,” “down,” “top” and “bottom” as well as derivative thereof(e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should beconstrued to refer to the orientation as then described or as shown inthe drawing under discussion. These relative terms are for convenienceof description and do not require that the apparatus be constructed oroperated in a particular orientation. Terms concerning attachments,coupling and the like, such as “connected,” refer to a relationshipwherein structures are secured or attached to one another eitherdirectly or indirectly through intervening structures, as well as bothmovable or rigid attachments or relationships, unless expresslydescribed otherwise.

For purposes of the description hereinafter, it is to be understood thatthe embodiments described below may assume alternative variations andembodiments. It is also to be understood that the specific articles,compositions, and/or processes described herein are exemplary and shouldnot be considered as limiting.

The hydrocarbons in crude oil are mostly alkanes, cycloalkanes andvarious aromatic hydrocarbons while the other organic compounds containnitrogen, oxygen and sulfur, and trace amounts of metals such as iron,nickel, copper and vanadium. The exact molecular composition varies butthe general compositions include about 15 wt. %-60 wt. % of paraffins(average about 30%), about 30 wt. % to 60 wt. % of naphthenes (average49%), and about 3 wt. % to 30 wt. % of aromatics (average 15%). Theremainder is asphaltic (average 6%). The crude oil can be then fracturedinto different fractions based on the range of the boiling points.

Starting from distilled fractions of crude oils, the inventors haveinvented a novel composition which can be directly used to effectivelysuppress fugitive dust and other particles with high efficiency. Such acomposition can be used to suppress a variety of different particles inversatile applications, including but are not limited to constructionsindustries, the coal industry, other mining industries, agriculture andfood processing industries. These particles include but are not limitedto silica, sand, concrete, soil, flour, airborne biohazard particles,and any other particles which may be suspended in the air. The presentinvention also provides the method of making and the method of usingsuch a composition for suppressing dust particles.

In some embodiments, the composition for suppressing dust particlescomprises saturated hydrocarbons and unsaturated hydrocarbons. Forexample, the composition comprises from about 51 wt. % to about 100 wt.% of saturated hydrocarbons, and from about 0 (or about 0.1%) to about49 wt. % of unsaturated hydrocarbons. Unless expressly indicatedotherwise, the content of an ingredient is characterized by a weightpercentage in the total composition. The saturated hydrocarbons mayinclude paraffin and cyclic saturated hydrocarbons. The unsaturatedhydrocarbons may be aromatic hydrocarbons. The composition also has acertain amount of wax. The wax can be a part of the saturated and theunsaturated hydrocarbons, or just a part of the saturated hydrocarbons.In some embodiments, the content of the wax is in the range from about 5wt. % to about 40 wt. % of the total composition.

In some embodiments, the saturated hydrocarbons and the unsaturatedhydrocarbons have a narrow distribution based on carbon atoms in eachmolecule. For example, the saturated hydrocarbons and the unsaturatedhydrocarbons are hydrocarbons in the range of from C6 to C61. In someembodiments, the saturated hydrocarbons are substantially in the rangeof from C16 to C26. In some embodiments, the saturated hydrocarbons cancomprise paraffin in the range of from about 61 wt. % to about 99.9% wt.% of the total composition. The unsaturated hydrocarbons are in therange of from about 5 wt. % to about 30 wt. % (e.g., from about 10 wt. %to about 20 wt. %) of the total composition.

The wax may be paraffinic wax. The wax may also be saturated hydrocarbonin the range from C27 to C61 (e.g., from C27 to C50, or from C27 toC40). The content of the wax can be in the range from about 5% to about30% (e.g., 10-20%) by weight of the total composition. In someembodiments, the wax has a boiling point of equal to or higher than 376°C. measured under atmospheric pressure. In another word, a portion ofthe fraction of hydrocarbons having a boiling point of equal to orhigher than 376° C. can be used as an approximate indication of thecontent of the wax. Unless expressly indicated otherwise, the boilingpoints in the present disclosure are measured under atmosphericpressure.

In some embodiments, the saturated hydrocarbons and the unsaturatedhydrocarbons may have a boiling point in the range from about 285° C. toabout 405° C., and from about 60% to about 95% by weight of totalcomposition has a boiling point of in the range of from 285° C. to 376°C. In some embodiments, the composition as dust suppressant has amelting point of in the range of from 0° C. to 37.7° C.

In some embodiments, the saturated hydrocarbons further comprise atleast one cyclic saturated hydrocarbon, which may be at any amount inthe total composition. For example, the content of the cyclic saturatedhydrocarbon is in the range from about 0.1% to about 10% by weight ofthe total composition. The cyclic saturated hydrocarbons may be providedthrough hydrogenation of aromatic hydrocarbons in a distilled fractionof a crude oil.

As an example, in such an exemplary composition, the saturatedhydrocarbons are in the range of from about 80 wt. % to about 95 wt. %.The wax is a portion of the saturated hydrocarbons such as paraffins andis in the range from about 10 wt. % to about 20 wt. % of the totalcomposition. The unsaturated hydrocarbons are aromatic hydrocarbons, andare in the range of from about 5 wt. % to about 20 wt. % of the totalcomposition.

To make the composition for suppressing dust particles described herein,a crude oil can be fractionally distilled to provide an initialfraction. Such an initial fraction may have chemical composition closeto that of the composition of dust suppressant described above, exceptthat the initial fraction may have a small amount of olefin (e.g., 1-5%or <2%), and a content of aromatic hydrocarbon higher than that in thecomposition of dust suppressant. In some embodiments, the initialfraction comprises saturated and unsaturated hydrocarbons in the rangeof from C6 to C61, for example, substantially in the range of from C16to C26. The initial fraction may also comprise wax at an amount similarto or lower than that of the composition described above. The boilingpoints of the initial fraction may be also in a range similar to (orslightly lower than) that of the composition described above.

The initial fraction can be then hydrogenated. The hydrogenating is usedto convert at least a portion of the unsaturated hydrocarbons tosaturated hydrocarbons. In some embodiments, the unsaturatedhydrocarbons in the fraction comprise aromatic hydrocarbons, and atleast a portion of the aromatic hydrocarbons is converted into cyclicsaturated hydrocarbons after the step of hydrogenating. Sometimes theunsaturated hydrocarbons in the fraction may comprise olefin (e.g., <5wt. % or <2 wt. %). The olefin is substantially converted into saturatedhydrocarbon after the step of hydrogenating. The degree of thehydrogenation in the step of hydrogenating is in the range from 10% to95% by weight (e.g., 10%-75% or 20%-40%) of the unsaturated hydrocarbonsin the fractions.

The hydrogenation may be performed using hydrogen and a catalyst (e.g.,Ni, Mo) under a certain temperature (e.g., 300-380° C.) and a certainpressure (e.g., 600-1000 psi). For example, the initial fraction can behydrogenated with pure hydrogen gas at a temperature in the range offrom 315° C. to 345° C. under a pressure in the range from 700 psi to900 psi. The wax in the initial fraction is not removed before and afterthe hydrogenation.

The chemical compositions and physical properties of both the initialfraction and the final composition as dust suppressant are characterizedusing the standard methods, mostly following the ASTM standards.

The term “API gravity,” as used herein, refers to the American PetroleumInstitute gravity of a petroleum liquid expressed as degrees API anddetermined in accordance with ASTM standard D 287 entitled StandardMethod of Test for API Gravity of Crude Petroleum and Petroleum Products(Hydrometer Method). The API gravity is an inverse measure of therelative density of petroleum liquid and the density of water.

The term “flash point,” as used herein, refers to the lowest temperatureat which it can vaporize to form an ignitable mixture in air. The flashpoint of all petroleum products with flash points above 79° C. (175° F.)and below 400° C. (752° F.) except fuel oils can be measured followingASTM Standard D92 entitled Standard Test Method for Flash and FirePoints by Cleveland Open Cup.

The term “aniline point” of an oil, as used herein, refers to theminimum temperature at which equal volumes of aniline and the oil aremiscible, i.e. form a single phase upon mixing. A lower aniline point isan indication of higher content of aromatic compound in the oil. Anilinepoint is measured following the ASTM Standard D611 entitled StandardTest Methods for Aniline Point and Mixed Aniline Point of PetroleumProducts and Hydrocarbon Solvents.

The term “viscosity index” (VI), as used herein, refer to the rate ofchange of viscosity of lubricating oil with temperature. An oil having ahigh viscosity index (e.g., above 80) exhibits a smaller change inviscosity with temperature variation than those with a low viscosityindex (e.g., lower than 35).

Compositions of saturated and unsaturated hydrocarbon, polar compounds,olefin and other ingredients are measured following the ASTM standardD2007 entitled Standard Test Method for Characteristic Groups in RubberExtender and Processing Oils and Other Petroleum-Derived Oils by theClay-Gel Absorption Chromatographic Method. This test method covers aprocedure for classifying oil samples of into the hydrocarbon types ofpolar compounds, aromatics and saturates, and recovery of representativefractions of these types based on boiling points.

The distillation tables showing content of ingredients in each boilingpoint interval are generated following the ASTM standard D2887.

The examples described below are just for illustration purpose.

Referring to FIG. 1, different grades of hydrocarbons can befractionated from crude oil through fractional distillation in a crudetower in accordance with some embodiments. In some embodiments, thecrude oil is preheated with fractionated products and then furtherheated in the furnace to 715 F (380° C.) before injecting into thebottom of the crude tower. In some embodiments, the fractionaldistillation is performed under atmosphere pressure. As shown in FIG. 1,the atmospheric distillation process fractionates a crude oil (e.g.,Pennsylvania Grade crude oil) into eight liquid streams and one fuel gasstream. These fractionated grades or streams include fuel gas, heavynaphtha, K-48, K-50, K-61, Waxy LLN (light lube neutral), Waxy MN(medium neutral), Waxy HN (heavy neutral), and C-stock (cylinder stock)in the order of increasing boiling points.

The inventors have identified the fraction of Waxy LLN as a suitableinitial fraction to make the composition for suppressing dust particlesin some embodiments. Referring to FIG. 2 (distillation chart), andTables 1-2, Waxy LLN has about 83.0% of saturated hydrocarbons, about15.9% of aromatic hydrocarbons, and about 1.1% olefins. The wax contentis about 16% (in the range of 15-17%). The wax content was separated andmeasured at a temperature in the range from −27.8° C. to −26.1° C. inthis disclosure. The saturated hydrocarbons and the unsaturatedhydrocarbons are hydrocarbons in the range of from C6 to C61,predominantly in the range of from C16 to C26. Referring to thedistillation table shown in FIG. 2 and Table 2, the ingredients of WaxyLLN have a boiling point in the range of from 300 to 400° C. The boilingpoint of the peak composition (which is about 50% of the totalcomposition in the distillation chart) is about 356° C. Based on themeasured wax content (about 16%), the portion having a boiling pointabove 376° C. can be used to roughly correlate with the wax content inthe composition in some embodiments (see Table 2).

The contents of impurities are negligible in Waxy LLN. For example, WaxyLLN has a nitrogen content of 1 ppm measured following ASTM standardD-5762, and a carbon residue of less than 0.1 wt. % measured followingASTM standard D-4530. The content of iron is 1.5 ppm by weight. Thecontents of other metals such as vanadium, nickel, copper and sodium areless than 0.1 ppm by weight. The bromine number measured according toASTM D-1159 is 3.4 g/100 gm. The total content of chlorides is less than1 ppm by weight. The content of silicon measured following ASTM standardD-5184 is 0.2 ppm by weight. The content of hydrogen sulfide in theliquid is less than 10 ppm by weight.

TABLE 1 Chemical Compositions and Physical Properties of Waxy LLN BeforeHydrogenation Property Results Viscosity at 40° C. (centipoise) 8.73Viscosity at 100° C. (centipoise) 2.45 Viscosity Index 102 ASTM color3.0 Flash point (° C.) 182.2 Solid point (° C.) 13.0 Moisture (ppm, KarlFisher) 35 Sulfur (ppm) 717 Saturates (wt. %) 83.0 Aromatics (wt. %)15.9 Polar compound (including olefins, wt. %) 1.1 Wax (wt. %) 15-17 APIGravity at 15.6° C. 36.7 Pour Point (° C.) 15 Aniline Point (° C.) 198.6

TABLE 2 Cumulative Fraction Percentage of Waxy LLN at Different BoilingPoint Intervals Cumulative Boiling Boiling Cumulative Boiling BoilingFractions Point Point Fractions Point Point Wt. % (° F.) (° C.) Wt. % (°F.) (° C.) 0 562 294.4 51 673 356.1 1 576 302.2 52 674 356.7 2 593 311.753 675 357.2 3 601 316.1 54 675 357.2 4 607 319.4 55 676 357.8 5 613322.8 56 676 357.8 6 617 325.0 57 676 357.8 7 621 327.2 58 677 358.3 8625 329.4 59 677 358.3 9 627 330.6 60 677 358.3 10 628 331.1 61 678358.9 11 628 331.1 62 679 359.4 12 630 332.2 63 680 360.0 13 632 333.364 681 360.6 14 635 335.0 65 682 361.1 15 637 336.1 66 683 361.7 16 639337.2 67 684 362.2 17 640 337.8 68 68 20.0 18 642 338.9 69 686 363.3 19643 339.4 70 687 363.9 20 645 340.6 71 688 364.4 21 646 341.1 72 689365.0 22 648 342.2 73 690 365.6 23 649 342.8 74 691 366.1 24 650 343.375 692 366.7 25 651 343.9 76 693 367.2 26 652 344.4 77 694 367.8 27 652344.4 78 695 368.3 28 653 345.0 79 696 368.9 29 653 345.0 80 697 369.430 654 345.6 81 697 369.4 31 654 345.6 82 698 370.0 32 655 346.1 83 699370.6 33 656 346.7 84 700 371.1 34 657 347.2 85 701 371.7 35 658 347.886 703 372.8 36 659 348.3 87 704 373.3 37 660 348.9 88 706 374.4 38 661349.4 89 708 375.6 39 662 350.0 90 710 376.7 40 663 350.6 91 712 377.841 664 351.1 92 714 378.9 42 665 351.7 93 716 380.0 43 666 352.2 94 718381.1 44 667 352.8 95 720 382.2 45 668 353.3 96 724 384.4 46 668 353.397 729 387.2 47 669 353.9 98 736 391.1 48 670 354.4 99 746 396.7 49 671355.0 100 756 402.2 50 672 355.6

Waxy LLN is hydrogenated as described. The chemical compositions andphysical properties of hydrogenated Waxy LLN are shown in FIG. 3, andTables 3-4. Hydrogenated Waxy LLN has about 87.95% of saturatedhydrocarbons. The olefins (1.1%) in Waxy LLN is converted into saturatedhydrocarbon (i.e. paraffin). In addition to 83% of the originalsaturated hydrocarbons, the content of paraffins is about 84.1%.Hydrogenated Waxy LLN comprises about 3.85% of cyclic hydrocarbons,which are converted from aromatic hydrocarbons. The degree ofhydrogenation is about 24%. About 12.05% of aromatic hydrocarbons arestill present after hydrogenation. The content of polar compound andolefin in hydrogenated Waxy LLN is approximately zero. The hydrogenatedcomposition has a melting point of less than 37.7° F. The boiling pointis in the range from 285° C. to 405° C. The wax content in Table 3 wasseparated and measured at a temperature in the range from −27.8° C. to−26.1° C.

TABLE 3 Chemical Compositions and Physical Properties of HydrogenatedWaxy LLN Property Results Viscosity at 40° C. (centipoise) 8.08Viscosity at 100° C. (centipoise) 2.34 Viscosity Index 104 ASTM color<0.5 Saybolt color 10.0 Flash point (° C.) 185 Solid point (° C.) 14.0Moisture (ppm, Karl Fisher) 19.8 Sulfur (ppm) 50.5 Saturates (wt. %)87.95 Aromatics (wt. %) 12.05 Polar compound (including olefins, wt. %)0 Wax (wt. %) 15-17 API Gravity at 15.6° C. 37.3

TABLE 4 Cumulative Fraction Percentage of Hydrogenated Waxy LLN atDifferent Boiling Point Intervals Cumulative Boiling Boiling CumulativeBoiling Boiling Fractions Point Point Fractions Point Point Wt. % (° F.)(° C.) Wt. % (° F.) (° C.) 0 544 284.4 51 672 355.6 1 560 293.3 52 673356.1 2 575 301.7 53 673 356.1 3 588 308.9 54 674 356.7 4 596 313.3 55674 356.7 5 599 315.0 56 675 357.2 6 604 317.8 57 676 357.8 7 609 320.658 677 358.3 8 612 322.2 59 679 359.4 9 615 323.9 60 680 360.0 10 619326.1 61 681 360.6 11 622 327.8 62 682 361.1 12 623 328.3 63 683 361.713 624 328.9 64 685 362.8 14 625 329.4 65 686 363.3 15 626 330.0 66 687363.9 16 628 331.1 67 688 364.4 17 631 332.8 68 689 365.0 18 633 333.969 691 366.1 19 635 335.0 70 692 366.7 20 636 335.6 71 693 367.2 21 638336.7 72 694 367.8 22 639 337.2 73 695 368.3 23 641 338.3 74 695 368.324 642 338.9 75 696 368.9 25 644 340.0 76 697 369.4 26 646 341.1 77 698370.0 27 647 341.7 78 700 371.1 28 648 342.2 79 701 371.7 29 649 342.880 703 372.8 30 650 343.3 81 704 373.3 31 650 343.3 82 706 374.4 32 651343.9 83 707 375.0 33 651 343.9 84 709 376.1 34 652 344.4 85 710 376.735 653 345.0 86 713 378.3 36 655 346.1 87 714 378.9 37 656 346.7 88 715379.4 38 658 347.8 89 716 380.0 39 659 348.3 90 717 380.6 40 660 348.991 720 382.2 41 661 349.4 92 722 383.3 42 662 350.0 93 725 385.0 43 663350.6 94 727 386.1 44 664 351.1 95 731 388.3 45 666 352.2 96 734 390.046 667 352.8 97 737 391.7 47 668 353.3 98 743 395.0 48 669 353.9 99 751399.4 49 671 355.0 100 761 405.0 50 672 355.6

In another aspect, the present disclosure provides a method of using thecomposition for suppressing particles described herein. The method usingthe composition comprises applying the composition to bring thecomposition in contact with the particles. The step of applying thecomposition may comprise a step of mixing the composition with theparticles, or a step of spraying the composition onto with theparticles, or any combinations thereof. The composition is sprayed intodrops having any suitable size. When the size of the drops issubstantially similar or close to (or the same as) the size of theparticles, the drops can be better combined with the particles in someembodiments. For example, if the particles contain silica in the rangesof from 180 microns to 389 microns, the drop size can be in the rangesuch as from 236 microns to 340 microns.

The method of using can further comprise heating the composition beforeor during the step of applying the composition, at a suitabletemperature according to its melting point. The temperature can be inthe range from about 10° C. to about 100° C. (e.g., from about 37° C. toabout 70° C. or from about 20° C. to about 25° C., or from about 20° C.to about 37° C.).

Hydrogenated Waxy LLN, as an exemplary composition, can be directly usedas a dust suppressant. It can be mixed and coated onto the particles orsprayed onto the particles. In some embodiments, hydrogenated Waxy LLNis heated at a temperature (e.g., about 21° C. or 37.7° C.) during theprocess of applying. Referring to FIGS. 4A-4C, an exemplary apparatus asshown is used for testing dust suppression in some embodiments. Typicaltesting results of hydrogenated Waxy LLN are shown in Table 5.

A testing procedure is used to simulate the application site. Referringto FIGS. 4A-4C, 300 g of particles (2) such as sand is placed into acontainer (4), which can be made of plastic or metal. One end of thecontainer (4) is open to air and provides a partially enclosedstructure. About 0.1 wt. % (about 15 drops) of a composition such ashydrogenated Waxy LLN is mixed with the particles. A Haz-Dust Dustmonitor (6) is placed inside the container (4) close to the open end.The container (4) is rotated constantly at a suitable rate, through ashaft (10) connected with a motor (12). The data of particles in theatmosphere inside the container (4) is collected by the Haz-Dust Dustmonitor (6) connected with a recorder (8) in the partially enclosedstructure with the analyzer placed 13 inches from the mouth of thecontainer (4). The inventors have determined this test replicates theexposure a worker in the field would have on an active frac site.Respirable particles such as respirable silica can be also introducedinto the container. The data in Table 5 are time weighted averages foran 8 hour shift.

Different particles were used. Sargent 40/70 is an API approved fracsand having a size in the range of from 40 mesh to 70 mesh availablefrom SARGENT Sand Company of Saginaw, Mich. UNIFRAC® 30/50 is ahydraulic fracturing sand having a size in the range of from 30 mesh to50 mesh available from Unimin Corporation-Energy Division of theWoodlands, Tex. US SILICA™ 100 mesh is a silica product having anaverage size of about 100 mesh available from U.S. Silica Corporation ofFrederick, Md.

Referring to Table 5, hydrogenated Waxy LLN provides excellentperformance in suppressing dust particles. For example, the dust densityis reduced to below the proposed OSHA PEL for the 40/70 and 30/50material.

TABLE 5 Hydrogenated Waxy LLN as Dust Suppressant Dust Density AfterDust Density Treatment with with No Inventive Dust Treatment CompositionReduction Particle Type (μg/m³) (μg/m³) Percentage Sargent 40/70 mesh1,310 <50 >96.18% UNIFRAC ® 30/50 1,240 <50 >95.97% mesh US SILICA ™ 1004,360 70   98.39% mesh

Referring to Table 6, different initial fractions were evaluated, andcompared to Waxy LLN and hydrogenated Waxy LLN. Nonwaxy LLN is derivedfrom Waxy LLN, but the wax therein has been removed. The Medium Neutral(MN) grade and the Heavy Neutral (HN) grade have boiling points higherthan that of Waxy LLN. Referring to Table 6, the portion having aboiling point above 376° C. is used as an indication of the wax content.Nonwaxy LLN, the Medium Neutral (MN) grade and the Heavy Neutral (HN)grade did not provide desirable results for suppressing dust particles.Based on the results, suitable wax content plays an important role indust suppression. The content of the wax may not be less than 5%, orhigher than 80%. The wax content can be in the range from about 5% toabout 40% (e.g., 5-30, or 10-20%) by weight of the total composition.

TABLE 6 Comparison of Different Fractions Boiling Boiling Point Wt. %Point at the for Boiling Range Peak Point Oil Type (° C.) (° C.) >376°C. Nonwaxy LLN 286-400 353 ≤5% Waxy LLN 300-400 356 11% Waxy LLN (after285-405 356 16% hydrogenation) Medium Neutral 300-528 424 85% (MN) GradeHeavy Neutral (HN) 342-657 520 99% Grade

Although the subject matter has been described in terms of exemplaryembodiments, it is not limited thereto. Rather, the appended claimsshould be construed broadly, to include other variants and embodiments,which may be made by those skilled in the art.

What is claimed is:
 1. A composition for suppressing dust particles,comprising: from about 51% to 90% by weight of saturated hydrocarbons;and from about 10% to about 49% by weight of unsaturated hydrocarbons;wherein the composition has a content of wax in the range from about 5%to about 30% by weight of the total composition, and the wax issaturated hydrocarbon.
 2. The composition of claim 1, wherein thesaturated hydrocarbons and the unsaturated hydrocarbons are hydrocarbonsin the range of from C6 to C61.
 3. The composition of claim 1, whereinthe saturated hydrocarbons comprise hydrocarbons substantially in therange of from C16 to C26.
 4. The composition of claim 1, wherein the waxis paraffinic wax.
 5. The composition of claim 1, wherein the wax issaturated hydrocarbon in the range from C27 to C61.
 6. The compositionof claim 1, wherein the wax has a boiling point of equal to or higherthan 376° C. measured under atmospheric pressure.
 7. The composition ofclaim 1, wherein the saturated hydrocarbons and the unsaturatedhydrocarbons have a boiling point in the range from about 285° C. toabout 405° C., and from about 60% to about 95% by weight of totalcomposition has a boiling point of in the range of from 285° C. to 376°C., the boiling points being measured under atmospheric pressure.
 8. Thecomposition of claim 1, wherein the saturated hydrocarbons furthercomprises at least one cyclic saturated hydrocarbon, and the at leastone cyclic saturated hydrocarbon is in the range from about 0.1% toabout 10% by weight of the total composition.
 9. The composition ofclaim 1, wherein the saturated hydrocarbons comprise paraffin in therange of from about 61% to about 95% by weight of the total composition.10. The composition of claim 1, wherein the composition has a meltingpoint of in the range of from 0° C. to 37.7° C.
 11. The composition ofclaim 1, wherein the unsaturated hydrocarbons are in the range of fromabout 10% to about 30% by weight of the total composition.
 12. Thecomposition of claim 1, wherein the unsaturated hydrocarbons arearomatic.
 13. The composition of claim 1, wherein the saturatedhydrocarbons are in the range of from about 80 to about 95% by weight ofthe total composition; wherein the wax is saturated hydrocarbon and isin the range from about 10% to about 20% by weight of the totalcomposition; and the unsaturated hydrocarbons are aromatic, and are inthe range of from about 10% to about 20% by weight of the totalcomposition.
 14. A method of making the composition of claim 1,comprising: fractionally distilling a fraction from a crude oil, thefraction comprising saturated and unsaturated hydrocarbons in the rangeof from C6 to C61; and hydrogenating the fraction to convert at least aportion of the unsaturated hydrocarbons to saturated hydrocarbons. 15.The method of claim 14, wherein the unsaturated hydrocarbons in thefraction comprise aromatic hydrocarbons, and at least a portion of thearomatic hydrocarbons is converted into cyclic saturated hydrocarbonsafter the step of hydrogenating.
 16. The method of claim 14, wherein theunsaturated hydrocarbons in the fraction comprise less than 5% by weightof olefin, and the olefin is converted into saturated hydrocarbon afterthe step of hydrogenating.
 17. The method of claim 14, wherein a degreeof the hydrogenation in the step of hydrogenating is in the range from10% to 95% by weight of the unsaturated hydrocarbons in the fractions.18. A method of using the composition of claim 1 for suppressingparticles, comprising: applying the composition to bring the compositionin contact with the particles.
 19. The method of claim 18, wherein inthe step of applying the composition comprises, the composition is mixedwith the particles.
 20. The method of claim 18, wherein the compositionis applied by spraying the composition onto with the particles.
 21. Themethod of claim 18, wherein the composition is sprayed into drops havinga size substantially similar or close to the size of the particles. 22.The method of claim 18, further comprising: heating the composition at atemperature of in the range from 20° C. to 100° C. before or during thestep of applying the composition.